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Title: A COMPUTER SYSTEM OF ESTIMATING REFERENCE CROP EVAPOTRANSPIRATION USING THE MODIFIED PENMAN’S (FAO - 24) METHOD

Author: Menelaos Theocharis

Year: 2009

Publisher: European Water Resources Association (EWRA)

Description:

The rational designing of irrigation systems requires the calculation of the evapotranspiration in the best possible way. Reference crop evapotranspiration (ETr) is the rate at which water, if available, would be removed from the soil and plant surface of a specific crop, arbitrarily called a reference crop. The classical Penman method is a combination equation that considers both the energy and aerodynamic aspects of the ETr process. Food and Agricultural Organization (FAO) modified the original Penman’s method in 1977. This method uses mean daily climatic data, with an adjustment for day and night time weather conditions. The modified Penman’s (FAO-24) method is considered to be one of the most accurate methods for the computation of evapotranspiration and must be used when all the required climatological data are available. The required calculating procedure when the above modified Penman’s (FAO-24) method is used, is very complex and calls for a lot of calculations. In this paper we present a computer system of estimating reference crop evapotranspiration using the modified Penman’s (FAO-24) method. The system facilitates irrigation network designers in calculating reference crop evapotranspiration. It is simple in use, do not demand special informatics knowledge, and it is approachable to a wide range of researchers. System’s architecture includes a user-friendly interface for the data input, a
computational module and the output subsystem, where the user is given a detailed table of results. The computer system provides a quick and accurate solution to the problem of estimating reference crop evapotranspiration. In addition, it could be incorporated as subroutine of integrated software dealing with hydraulic calculations.